Cut unsalted butter into cubes and finely grade the parmesan as well as the cheddar cheeses into a bowl. Add the flour, butter, mustard powder, Cayenne pepper powder and the cheese into a blender. Blend the mix in bursts for a few minutes or until the mix has come together and formed dough.

Wrap the dough in a plastic film and store in the refrigerator for 30 minutes or more. This is done because it is very difficult to work with the dough if it is not cold enough.

Sprinkle some flour over the dough and on the surface you intend to roll out the dough on. Roll evenly into about 2.5 mm thick layer (about 1/10 inches). Cut the dough into 3×6 cm rectangles with a knife ( you could also use round stencils or any other form to your liking ). Spread the cut dough on a non-sticking baking plate, but be sure to keep about 2cm ( 3/4 inches) between them on all sides.

Whisk one egg and coat the dough and sprinkle some parmesan over each biscuit and bake for 10 minutes at 180°C ( 350°F ).

We were feeling a little adventurous so we decided to top some biscuits with sweet mustard and pepperoni but others with sweet mustard and honey. Just use your imagination and experiment!